Timing And Magnitude Of Increases In Levothyroxine Requirements And The Birth During Pregnancy In Women After Thyroid Carcinoma Surgery

Thyroid carcinoma (TC) is the most common malignant tumor of thyroid. Pillarythyroid carcinoma(PTC), which accounted for60%of adult thyroid cancer andmore common in30-45years old women(still in childbearing age), has goodprognosis after operation. Whereas, they need for lifelong taking thyroxinetablets as hormone replacement therapy. On the basis of America ThyroidAssociation’s guidelines, the first part of this article introduces someconsensus of dose control, monitoring and the effects on their pregnancy andfetus of childbearing age women who take thyroxine tablets after PTCoperation. The second part provides a retrospective analysis of the prognosis of20women after thyroid cancer operation and their pregnancy in our hospital.Objective：Hypothyroidism during pregnancy has been associated with impairedcognitive development and increased fetal mortality. In this retrospective studywe attempted to identify precisely the timing and amount of levothyroxineadjustment required during pregnancy.Methods: Twenty women planning pregnancy after thyroidectomy because ofthyroid cancer were observed before and throughout their pregnancies. Thyroidfunction were measured before conception, approximately every four weeksduring the whole period. The dose of levothyroxine was increased to maintainthe thyrotropin concentration at preconception values throughout pregnancy. Results:21pregnancies occurred in20women and resulted in20full-termbirths. One women have one abortion. Their basal doses are all100μg. The doseincreased by12.5μg a time to target the thyrotropin concentrations (0.1-0.25μUper milliliter).The mean levothyroxine requirement increased50percent duringthe first half of pregnancy and plateaued by week16. This increased do se wasrequired until delivery. All the newborns are healthy and so does their motheraccording to their5-year-followups.Conclusions: we propose that women after thyroid cancer surgery increasetheir levothyroxine dose as soon as pregnancy is confirmed. Thereafter, serumthyrotropin levels should be monitored and the levothyroxine dose adjustedaccordingly.